Paper making machine



Mays, 1934 l R. Mec. .JoHNsToNE 1,957,963

PAPER MAKING MACHINE Filed sept. 2, 1952 A TTORNEY.

-process 35 that traves in Patented May .8, 1934 PATENT oFFlcE-f PAPERMAKING MACHINE Robert McC. Johnstone, Short Hills, N. J.

invention relates to paper making machines and relates more particularlyto' the removal fv water from the aqueous solution carried by the screenor Fourdrinier wire during the lof forming a paper web.

ain object and feature of the invention nfisithe, reduction of meanswhereby` the water of they-aqueous 'solution will be more rapidly andyetA withal more gently removed than has heretoforef.' been possible.

i I irthe accompanying drawing the invention is disclosed severalconcrete and preferred forms in :which:

Fig. Itis a more or less diagrammatic view of sol much-of 'a Fourdriniermachine as is necessary tol anunderstanding of the invention;

Fig. `2, enlarged detail view of a'portion of Fig. 1 showing theimproved supporting ele ments for the screen;

3 is a detail `view in side elevation showing one form Vofsupportingelement that may be ,used in carrying out the invention; A

Figs. 4 and 5 are views similar to Fig. 3 show-k ing other' forms ofsupporting elements that can be employed in carrying out the invention;

Fig. 4 is a transverse sectional view substantially on the plane of line4-4" of Fig. 4;

Fig. 5 isa transversesectional view substantially on the plane of line5\-5* of Fig. 5; and

6 is a transverse sectional view of still another form of supportingelement..

As indicated in Fig. 1, A is an element that feeds an aqueous solutioncontainingcellulose libres tothe upper run of a fine-mesh screen B thedirection of arrow C. 'Any 'suitable means, such as lower couch roll Dmay be utilized to 'drive the screen. F indicates deckle strapswhichpmay or maynot be employed. 3 designates a series of rotatableIrollers 40 that have the double function of supporting the upper run ofthe screen and of removing water from the aqueous solution. In the 'artof paper making, as heretofore practiced, rollers 3 have beensmooth-face in consequence of which but a slight amount of water islremoved by each roller or vsupporting element. For this reason it hasbeen customary to employ one or more suction boxes such as E which drawa. considerable amount of water from the aqueous solution. 50.,.Thesuction exerted by E isrelatively great and, in conseguence of this,considerable friction is develope between the traveling screen andthetop of the suction box, the result of which is that the screen wears outrelatively quickly and has '55 to be replaced, an expensive operation,because` Application september z, 1932, serial No. 631,468

' z claims. (ci. ca -44) it involvesnot-merely the cost of a new screenand the labor attendant upon the replacement but also the loss ofvproduction of paper while the machine is idle; Furthermore, it iscustomary to impart a vibrating motion to the screen 30. adjacent intakepoint A in order that the fibres I in thesolution may not arrangethemselves too uniformly in the direction of the iiow of saidl solution,and for this reason the suction boxes cannot be located near said intakeend but must be arranged near the output end of the screen.

It will therefore be understood that it is 4highly desirable to removewater more rapidly from the aqueous solution than it is now lpossibletodo with the smooth-faced rollers so as to avoid 70 the use or reduce thenumber of suction boxes or atleast to minimize the amount ofsuctionexerted by said boxes, for to do this would prolong the life ofthe screen', would speed up the production of the machine, and wouldeliminate or at least reduce the .necessity for the expen sive machinerythat creates the vacuum or suction. 1 v

'I'he invention consists in providing in the supporting surface of oneor more rollers 3 lshallow 80 cavities such that capillary attractionwill be set up between the traveling screen and the bottom yand otherwalls of the cavities whereby a larger amount of water will be removedby such rollers than heretofore. Such cavities may take many y forms, aswill be hereinafter explained, and should be of such area that, withoutsubstantially diminishing the screen supporting function of th'e roller,the rotation of said roller causes the water to be discharged from saidcavities. In 9o lthis way the water will be removed more rapidly and yetmore gently from the solution than when a powerful suction is employed.It is, however,

`not intended under all circumstances to necessarily exclude the use ofsuction boxes, but if such be used the suction can bematerially reduced.

The word cavity is here used in'a very broad sense as will be seen fromthe following. In Fig. 3 is'shown one of the rollers in which thecavities consist' of ,oppositely extending spiral grooves or 100 canalsJ; The depth of these canals or cavities will obviously vary with'theamount of water7 it is necessary to remove. lNear the intake vend of thescreen, a. depth of from say .008 to .006 inchesis suitable, while thedepth of the grooves of these rollers that are nearer the output end ofthe screen could be say .003 inches. The width of the `grooves could besay one-half inch. It will be:

apparent that the grooves need not be helical as shown m Pig. a, b utcould be straight circumferio l selves to those skilled in the art.

ential or non-helical in character, in which case it might be advisableto arrange the grooves of' adjacent rollers in staggered relation. Or,if desired, the helical formation of the grooves could be still moreaccentuated as indicated by the grooves J in Fig. 4. Again if desiredthe cavities could be in the form of circular or other depressions as J"in Fig. 5. Or, as indicated at L in Pig. 6, the cavities could be spacesfo ed between projections in Athe surface of the roller. Many otherforms will naturally suggest them- The operation of the device will beobvious fro the foregoingv explanation, and it remains only screen tocarry an aqueous solution from whichl paper is to be made; v and arotatable supporting element, associated with said screen, thesupporting surface of which is provided with shallow cavities' such thatcapillary attraction is set up between the screen and the surfaces ofthe cavities to thereby draw water into said cavities, and said cavitiesbeing of such area that, without substantially diminishing thesupporting function of said element, the rotation of such element causesthe water to be discharged from said cavities,

2. In a paper making machine: a traveling screen to carry an aqueoussolution from which paper is to be made; and a plurality of rotatablesupporting elements, associated with said screen, the supporting'surfaces of which are provided with shallow cavities such thatcapillary attraction is setup between the screen and the surfaces of thecavities to thereby draw water into said cavities, the depth of thecavities in the different supporting elements varying and being less inthose supporting elements that are near the output end of the screenthan in those supporting elements that are near the intake end of thescreen, and said cavities b eingpf such area'that, without substantiallydiminishing the supporting function of said elements, the rotation ofsuch elements causes the water to be discharged from said cavities.

ROBERT MCC. J OHNSTO'NE.

